This invention is generally related to an intake manifold and a method of assembling an intake manifold. More particularly, this invention relates to an intake manifold fabricated from an inner shell inserted and welded within an outer shell utilizing a laser welding process.
Plastic intake manifolds have been developed for use in motor vehicles that provide reduced weight and cost. A plastic intake manifold is typically constructed from a plurality of parts that are molded separately and then joined to one another. Various methods are known for joining plastic parts including vibration welding. Joint configurations for these plastic parts typically include a complicated cross-section for providing sufficient melt down material as well as features for trapping flash. Such joint geometries contribute substantially to the cost of fabricating an intake manifold.
Further, vibrational welding methods lead to the design of plastic manifolds that are designed to include a series of horizontal or vertical slices. Horizontal and vertical slices result in a plurality of parts that must be joined. Further the many parts each require a separate molding tools and assembly stations that complicate assembly and increase overall cost. Additionally, if any of the joints in such a process are defective the intake manifold assembly cannot be repaired.
Laser welding has been used to join plastic parts with success. Laser welding of plastic is accomplished by directing a laser through a laser translucent material onto a laser absorbent material. Laser Transmission Contour Welding is known for use with large asymmetrical parts. Kinematics of robots has advanced to permit following a complex contour such as is typical of an intake manifold assembly. However, typically laser welding is simply applied to joints originally designed according to known conventions for producing a vibration-welded joint. There is still a plurality of parts that require many joints. Further, in some instances, parts are inaccessible once the manifold is complete. Such construction increases the likelihood that an improper joint may result in the entire intake manifold being unusable. Laser welding requires that the parts touch without substantial gaps and access to the joint for the laser-welding tool.
Accordingly, it is desirable to design a plastic intake manifold to take advantage of laser welding processes to reduce the number of parts and to reduce the number of joints.